Dual Plasmon Resonances and Tunable Electric Field in Structure-Adjustable Au Nanoflowers for Improved SERS and Photocatalysis

Abstract

Flower-like metallic nanocrystals have shown great potential in the fields of nanophononics and energy conversion owing to their unique optical properties and particular structures. Herein, colloid Au nanoflowers with different numbers of petals were prepared by a steerable template process. The structure-adjustable Au nanoflowers possessed double plasmon resonances, tunable electric fields, and greatly enhanced SERS and photocatalytic activity. In the extinction spectra, Au nanoflowers had a strong electric dipole resonance located around 530 to 550 nm. Meanwhile, a longitudinal plasmon resonance (730~760 nm) was obtained when the number of petals of Au nanoflowers increased to two or more. Numerical simulations verified that the strong electric fields of Au nanoflowers were located at the interface between the Au nanosphere and Au nanopetals, caused by the strong plasmon coupling. They could be further tuned by adding more Au nanopetals. Meanwhile, much stronger electric fields of Au nanoflowers with two or more petals were identified under longitudinal plasmon excitation. With these characteristics, Au nanoflowers showed excellent SERS and photocatalytic performances, which were highly dependent on the number of petals. Four-petal Au nanoflowers possessed the highest SERS activity on detecting Rhodamine B (excited both at 532 and 785 nm) and the strongest photocatalytic activity toward photodegrading methylene blue under visible light irradiation, caused by the strong multi-interfacial plasmon coupling and longitudinal plasmon resonance.

LSP-SPP Coupling Structure Based on Three-Dimensional Patterned Sapphire Substrate for Surface Enhanced Raman Scattering Sensing

“…The self-cleaning process of the substrate is evidenced in two aspects. On the one hand, it has been demonstrated previously that Ag NPs can catalyze the degradation of small organic molecules [42]. On the other hand, the microstructure of PSS can significantly improve the light-capturing ability.…”

High-Yield Gold Nanohydrangeas on Three-Dimensional Carbon Nanotube Foams for Surface-Enhanced Raman Scattering Sensors

“…Nanoflowers have a representative structure of these 3-D plasmonic nanocrystals, presenting ultra-sensitive SERS signals. , For the construction of flower-like structures, many synthesis methods have been reported. For example, Guo et al proposed a rapid synthesis route to deposit Au nanoflowers on the surface of tin-doped indium oxide glass by the electrochemical deposition method .…”

Dual Function of 4-Aminothiophene in Surface-Enhanced Raman Scattering Application as an Internal Standard and Adsorbent for Controlling Au Nanocrystal Morphology

“…High-performance substrates are the core of surface-enhanced Raman scattering (SERS) technologies and are a focus of extensive attention and research. − To improve detection sensitivity, researchers have developed a variety of highly branched and/or hierarchical structures, including nanostars, − nanoflowers, , and sea urchins. , High-efficiency Raman signal enhancement can be achieved by generating a strong plasmon resonance electric field at the edges and tips . At the same time, photocatalysis studies showed that high-index crystal face nanocrystals have a higher chemisorption energy, − which is more conducive to plasma resonance, can theoretically achieve higher Raman signal enhancement amplification, and can improve the detection sensitivity.…”